A093354 Number of prime triples (p,q,r) with p < q < r <= n and q - p = r - q.

0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 5, 5, 5, 5, 7, 7, 7, 7, 7, 7, 9, 9, 11, 11, 11, 11, 11, 11, 11, 11, 11, 11, 13, 13, 16, 16, 16, 16, 17, 17, 17, 17, 17, 17, 20, 20, 20, 20, 20, 20, 23, 23, 24, 24, 24, 24, 24, 24, 26, 26, 26, 26, 30, 30, 32, 32, 32, 32, 32, 32, 36

Offset: 1

Author

Reinhard Zumkeller, Apr 27 2004

Keywords

• nonn

Examples

			a(20)=5:
(3,5,7), 5 - 3 = 7 - 5;
(3,7,11), 7 - 3 = 11 - 7;
(5,11,17), 11 - 5 = 17 - 11;
(3,11,19), 11 - 3 = 19 - 11;
(7,13,19), 13 - 7 = 19 - 13.